First, in the beginning, my rule of thumb was 4 hours of prep for every hour of game time.
Prep has gotten shorter as the years go by, but all RPGs are complex. Look at the sheer numbers of possible NPCs in the game.
I've done both table-top Amber and internet Amber gaming. There are pros and cons to both. Good luck.
Use the idea of Destiny from the Shadow Creation section. No matter what your PCs do, it WILL intersect with a plot originating in Amber. It will save you from how do I control the players headaches. Blackmail is one of the tools in the DMs bag of tricks. Make the NPCs need something from the PCs and don't let the NPCs be nice about it. Regardless of their backgrounds, the players are as new to the Amber-verse as you are.
Cheat.
Zelazny got this one right.
The Elders are smarter than you. After every session (and during if you can handle it) do a "what-if" fill-in-the-blank Elder knew what was going to happen? I have an NPC who has the Amber version of Guild navigators from Dune scanning the dream realms for hints of what might be. He is a grand master of assassins. He is evil. He is fun to run.
Enjoy!